Characterization of P2 Receptors Coupling to Signal Transduction in Canine Tracheal Epithelial Cells

• Main Authors: Wu, Wen-Bin, 吳文彬
• Other Authors: Yang Chuen-Mao
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/98678287966821671987

碩士 === 長庚醫學暨工程學院 === 基礎醫學研究所 === 85 === In this study, the experiments were conducted to characterize the P2 receptor subtype coupling to signal transduction on tracheal epithelial cells (TECs). The nucleotides ATP and UTP caused a concentration-dependent increase in inositol phosphates (IPs) accumulation and calcium mobilization.The rank orderof agonist potency was ATP = UTP >> 2-methylthio ATP (2-MeSATP) = alpha,beta-methylene ATP (alpha,beta-MeATP). Stimulation of TECs with maximallyeffectiveconcentrations of ATP and UTP showed no additive effect. ATP andUTP induced mutual cross-desensitization in IPs accumulation and calciummobilization.These findings suggest that both ATP and UTP act upon a commonnucleotide receptor defined as P2Y2 (P2U) receptor. Pretreatment of TECs withpertussis toxin and cholera toxin had no effect on ATP- and UTP-induced IPsaccumulationand calcium mobilization. Incubation of TECs in the absence of external Ca2+, caused a decrease in IPs accumulation and calcium mobilzationevoked by ATP, UTP. In contrast, omission of Mg2+ from buffer did not signi-ficantly change IPs response to ATP and UTP. The IPs accumulation and [Ca2+]iincrease in response to ATP and UTP were inhibited by Ni2+. Prior treatment with staurosporine, a protein kinase C inhibitor, reversed the effect of PMAon the ATP- and UTP-induced signal transduction. The effect of PMA was due tothe inhibition of G protein(s) or phospholipase C activity or uncoupled Gprotein(s) from PLC. It revealed that TECs expressed PKC alpha, betaI, betaII,gamma, epsilon, theta, delta, and zeta. With PMA treatment of cells for various times, translocation of PKC alpha, betaI, betaII, gamma, epsilon, theta,and delta from cytosol to the membrane was seen after treatment.